Answer:
78.88%
Step-by-step explanation:
We have been given that

The z-score formula is given by

For 

For 

Now, we find the corresponding probability from the standard z score table.
For the z score -1.25, we have the probability 0.1056
For the z score 1.25, we have the probability 0.8944
Therefore, the percent of the trees that are between 20 and 30 years old is given by
0.8944 - 0.1056
= 0.7888
=78.88%
Answer:
1/7
Step-by-step explanation:
2a + 3b = 6
5a + 2b = 4
We multiply the first equation by 5 and the second by 2 and and subtract the second from the first:
10a + 15b = 30
-10a -4b = -8
11b = 22
b = 2
2a + 3(2) = 6
2a = 0
a = 0
Checking,
5(0) + 2(2) = 4
4 = 4, true
12+2+8+6+57=85
85/5= 17
mean=17
Answer:
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Step-by-step explanation:
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